Introduction
Mungbean (Vigna radiata
L.) is an important grain legume crop. It is a short duration crop which occupies
7 million hectares, mainly in Asia and rapidly spreading across the globe,
owing to its high protein, fiber, antioxidants and phytonutrients (Itoh et al. 2006; Nair et al. 2019). This crop is highly suitable for arid regions of
Saudi Arabia, as it can tolerate drought stress and don’t need large amount of
irrigation water due to its well-developed tap and lateral root system, which
facilitates in rapid water absorption (Ahmed et al. 2015).
Sustainability of agriculture not only
needs effective mineral fertilization containing macro and micronutrients, but
also plant bio-stimulants having biologically active compounds (Calvo et al. 2014; Du-Jardin 2015). The prime
function of these bio-stimulants is to accelerate natural processes stimulating
the nutrient uptake and assimilation (Halpern et al. 2015; Yakhin et al.
2017). Humic substances impacting plant growth both directly and indirectly are
formed by microorganisms as a result of chemical and biological humification of
animal and plant matter (Shah et al. 2018). Indirectly
humic substances improve soil microbiota, soil structure and soil chemistry,
while directly these affect photosynthesis, respiration rate, enzymatic
activities, protein formation and carbohydrates assimilation (Dawood et al. 2019). Humic acid (HA) is an important component of humic substances
that improves the soil water holding capacity (Khaled and Fawy 2011). Being a bio-stimulant, HA regulates enzymatic activity that triggers
various plant physiological processes leading toward an increase in yield
components (Waqas et al. 2014). HA is
an important and integral part of soil organic matter which is not only a plant
bio-stimulant, instead it is a soil conditioner that improves soil texture,
structure and physiochemical features (Calvo et al. 2014).
Saudi Arabia comprises vast arid
regions with sandy soils having poor water and nutrient holding capacity,
therefore the use of HA is logically recommended for arable crops cultivation. However,
prevailing arid climatic conditions with vast sandy soils poses serious
challenges to sustainable agricultural activities. Among legumes, mungbean has
been targeted due to its importance in Saudi lifestyle and can be grown on
marginal soils with some success. Therefore, this study was designed to optimize
the types and rates of HA application to improve mungbean growth,
photosynthesis, and grain yield and quality. It was hypothesized that being a good soil
conditioner, HA application has the potential to improve mungbean growth and
yield on sandy soil in arid climatic conditions of Saudi Arabia.
Materials
and Methods
Seeds
of mungbean variety ‘NM- 2006’were collected from NIAB (Nuclear Institute of
Agriculture and Biology), Faisalabad, Pakistan and
used as experimental material. This two-year study was conducted to assess the
effectiveness of HA types and rates on agronomical, physiological, yield and
quality parameters of mungbean. Field experiments were conducted at King
Abdulaziz University, Jeddah, Saudi Arabia in two consecutive years 2016–2017
and 2017–2018.
Mungbean was sown with HA
application in both solid and liquid form at four different rates (0, 20, 40
and 60 kg ha-1). HA in solid phase was spread and manually
incorporated to the top 20 cm layer of soil before cultivation during each
growing season. However, the liquid phase of HA was equally divided into three
doses that afterward applied at the rates of 0, 20, 40 and 60 kg ha-1.
After complete dissolution in water, each dose was manually sprayed on soil
surface. First dose was applied after complete germination followed by second
dose two weeks after, while third dose was applied at the start of flowering.
Experiment was laid out following randomized complete block design (RCBD) under
split plot arrangement keeping HA types in main plots and rates in sub-plots,
respectively. Experiment was repeated four times with net plot size of 2 m × 3
m.
Crop husbandry
Prior to cultivation, soil was
prepared by two ploughing followed by cross ploughing and laddering. Afterward,
33–40 seeds per meter square were sown using drill at the depth of 3–4 cm in
well leveled, moist and weed free soil in 25 cm spaced rows with plant to plant
distance of 10 cm. To keep the soil moist, the drip irrigation system was used
on daily bases for all stages of plant. Crop was fertilized at the rate of 40
kg each of nitrogen, phosphorus and potassium ha-1 using of NPK
(20-20-20) fertilizer as source. Fertilizer was applied in three splits at 20,
40 and 60 days after sowing as fertigation (Akhtar et al. 2017). In order to remove weeds, manual weeding was done
after every 20 days.
Data collection
Growth parameters like plant
height, leaf area index, and shoot and root dry weights were measured following
Akhtar et al. (2017). Average height
of 10 randomly selected plants from each sub-plot was measured with meter rod
before harvesting and averaged. Leaf area index was measured at each
phenological stage using Plant Canopy Analyzer. Average root and shoot dry
weights of completely dried ten randomly selected plants were calculated using
digital electric balance. Physiological parameters, for instance stomatal
conductance, transpiration rate and photosynthesis rate were measured during
morning time before 10 a.m., from the abaxial surface of fully expanded leaves
by using Syrus 3 upgraded model SC-1, 2011 (Decagon
Devices, 2011). Total chlorophyll and carotenoids were determined by
using the protocol of Mahmood et al.
(2016).
Above mentioned randomly
selected ten plants were used to record average number of branches and pods per
plant, and pod length. For grain and biological yield, two central rows were
harvested and kept in field for three days for drying, tied into bundles and
weighed using spring balance to record biological yield. After that pods were
threshed manually, grains were separated and weighed using electrical balance
to record grain yield.
For seed quality parameters,
automatic Kjeldahl Analyzer was used to measure grain nitrogen contents,
spectrophotometer at 410 nm was used to record grain phosphorus contents while
flame photometer was used to estimate grain potassium contents. Moreover, total
protein and carbohydrates content were recorded following the protocol of Madar
et al. (2017).
Scanning electron microscopy
The SEM micrography
of leaves from selected plant samples was done with objective to compare the
effect of HA types and rates on the uptake of nutrient elements. Energy
dispersive X rays (EDX) system was used within the microscope due to its high
resolution, fast counting and analytical tendency. Moreover, this technique is
beneficial owing to its tendency to characterize the sample without prior need
of preparation. The leaves samples from mungbean were placed inside the
detectors of EDX system under X-rays photons. The data obtained after EDX
analysis consists of SEM spectrographs whose peaks indicate the assimilated
elements within leaf samples. In EDX generated spectrograph x-axis indicates
the energy, while y-axis represents the number of X-rays counts. The positions
of peaks in spectrograph facilitated the identification of elemental, while
their heights helped to quantify the nutrient elements inside leaves. Moreover,
SEM was already installed with features of auto-identification and
quantification of the elemental peaks.
Statistical
analysis
To check the significance of
applied treatments, data attained for all traits were subjected to two-way analysis
of variance (ANOVA) using computer-based
software statistics 8 (v. 8.1, © 1985–2005). In case of significant effects,
means were compared using least significant difference (LSD) test at 5% level
of probability (Steel et al. 1997).
Growth
parameters
Both
HA types and rates significantly improved the growth of mungbean while their
interactive effect was non-significant in both years of study (Table 1). Solid
form of HA significantly improved plant height, LAI, shoot fresh and dry
weight, and root fresh and dry weight of mungbean compared with its liquid form
in both years of study (Table 1). Likewise, with increasing HA rates, the
highest improvement in growth parameters was noticed at 60 kg ha-1 in both
years of study (Table 1).
Physiological
traits
Both
HA types and rates significantly improved the values of physiological
parameters of mungbean while their interaction depicted non-significant effect
during both years (Table 2). Solid form of HA significantly improved
photosynthesis rate, stomatal conductance, transpiration rate, total
chlorophyll and carotenoids of mungbean compared with its liquid form in both
years of study (Table 2). Likewise, with increasing HA rates, maximum rate i.e.,
60 kg ha-1 showed maximum improvement in physiological parameters
during both years of study (Table 2).
%201273-1278_files/image002.jpg)
Fig. 1: SEM micrographs
demonstrating the difference in elemental distribution in the leaves of mungbean under different types and rates of humic acid
a.
Distribution
of elements under solid HA at the rate of 60 kg ha-1
b.
Distribution
of elements under liquid HA at the rate of 60 kg ha-1
c.
Distribution
of elements under solid HA at the rate of 40 kg ha-1
d. Distribution
of elements under liquid HA at the rate of 40 kg ha-1
Yield
and related traits
Both
HA types and rates significantly affected the yield and related traits of
mungbean while their interactive effect was non-significant in both years of
study (Table 3). Solid form of HA significantly increased branches plant-1,
pods plant-1, pod length, 100-seed weight, seed yield and biomass
yield of mungbean compared with its liquid form in both years of study (Table
3). Moreover, with increasing HA rates, maximum rate i.e., 60 kg ha-1 showed maximum improvement in yield component in both
years of study (Table 3).
Seed quality
parameters
In
both years of study HA types and rates significantly improved the grain P and K
contents while had non-significant effect on grain N, carbohydrates and protein
contents of mungbean. Besides the interactive effect of HA types and rates
remained non-significant (Table 4). Solid form of HA significantly enhanced P
and K content of mungbean compared with its liquid form in both years of study
(Table 4). Moreover, with increasing HA rates, maximum rate i.e., 60 kg
ha-1 showed maximum improvement in seed quality parameters in both
years of study (Table 4).
SEM micrographs
SEM micrographs of randomly selected best
performing mungbean plants for both types of HA at rate 40 and 60 kg ha-1
were generated (Fig. 1). They showed visible variation in the assimilation and
distribution of nutrient elements in the leaves of mungbean at varying rates of
both types of HA. Moreover, the SEM micrographs of targeted area revealed the
highest uptake of mineral elements for solid HA at 60 kg ha-1
concentration as compared to concentration and type as indicated by the broader
peak area of Figure 1a. Besides, variation in peak positions of minerals was
noticed in micrographs for different types of HA at different rates, which
reflect varying impact of HA types and rates on the distribution of minerals in
leaves (Fig. 1a–d).
Results of this two-year field
study unveiled that HA application, solid type specially, improved growth, gas
exchange traits, yield related traits and grain quality of mungbean on sandy
soil under arid climatic conditions of Saudi Arabia (Table 1–4). Higher grain
yield of mungbean at higher rate i.e., 60 kg ha-1 of HA
application was due to notable expansion in entire yield related traits. Moreover,
significant expansion in yield-related traits was primarily due to substantial
improvement in photosynthesis owing to higher stomatal conductance and
synthesis of photosynthetic pigments (Shafeek et al. 2013; Tables 1–3). In another recent study, Akhtar et al. (2017) also concluded higher
mungbean yield with HA application of 60 kg ha-1 in both solid and
liquid forms due to significant elevation in yield-related traits like number
of pods and grains plant-1, and grain size.
Table 1: Effect of humic
acid types and rates of application on growth of mungbean
|
Treatments |
Plant
height (cm) |
Leaf
area index |
Shoot
dry weight (g plant-1) |
Root
dry weight (g plant-1) |
||||
|
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
|
|
HA types |
||||||||
|
Solid |
36.63 a |
43.7 a |
2.58 a |
2.67 a |
21.2a |
26.7a |
2.26 a |
2.58 a |
|
Liquid |
32.75 b |
38.51 b |
2.20 b |
2.28 b |
16.6 b |
23.0 b |
2.16 b |
2.44 b |
|
LSD value at 0.05 |
1.37 |
1.70 |
0.04 |
0.04 |
0.37 |
0.21 |
0.08 |
0.11 |
|
HA rates (kg ha-1) |
||||||||
|
0 |
30.78 b |
38.3 b |
1.85 d |
1.90 d |
14.3 d |
17.7 d |
1.90 d |
2.15 d |
|
20 |
31.52 b |
39.5 b |
2.04 c |
2.11 c |
17.5 c |
22.1 c |
2.07 c |
2.35 c |
|
40 |
34.32 a |
42.7 a |
2.72 b |
2.80 b |
24.1 b |
27.6 b |
2.33 b |
2.66 b |
|
60 |
34.28 a |
42.9 a |
2.80 a |
2.89 a |
22.0 a |
30.4 a |
2.43 a |
2.80 a |
|
LSD value at 0.05 |
1.17 |
1.48 |
0.03 |
0.01 |
1.05 |
0.25 |
0.08 |
0.11 |
|
Significance |
|
|
|
|
|
|
|
|
|
HA (Types) |
** |
** |
** |
** |
** |
** |
** |
** |
|
HA (Rates) |
** |
** |
** |
** |
** |
** |
* |
** |
|
Types × Rates |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
Means following the same letters, within a column for each trait, are
not statistically different from each other at P ≤ 0.05
HA=Humic Acid; **=
Significant at P ≤ 0.01; ns= Non-Significant
Table
2: Effect of humic acid types and rates of application on physiological
parameters of mungbean
|
Treatments |
Photosynthesis Rate (µmm-2 S-1) |
Stomatal Conductance (mmm-2 S-1) |
Transpiration Rate (mmm-2 S-1) |
Total Chlorophyll (g kg-1) |
Carotenoids (mg kg-1) |
|||||
|
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
|
|
HA types |
|
|
|
|
||||||
|
Solid |
28.54 a |
35.82 a |
885.60 a |
940.95 a |
12.98 a |
16.50 a |
1.60 a |
1.68 a |
3.00 a |
3.38 a |
|
Liquid |
23.63 b |
29.62 b |
790.90 b |
843.52 b |
12.001 b |
15.34 b |
0.87 b |
0.95 b |
2.15 b |
2.05 b |
|
LSD value at 0.05 |
0.32 |
0.40 |
7.88 |
8.25 |
0.05 |
0.07 |
0.06 |
0.056 |
0.05 |
0.05 |
|
HA rates (kg ha-1) |
|
|
|
|
||||||
|
0 |
18.05 d |
22.61 d |
772.55 d |
821.81 d |
11.18 d |
13.19 d |
1.25 d |
1.34 c |
2.65 d |
2.85 d |
|
20 |
23.05 c |
28.90 c |
812.17 c |
863.70 c |
12.91 c |
15.22 c |
1.50 c |
1.52 b |
2.85 c |
3.00 c |
|
40 |
30.70 b |
38.60 b |
879.48 b |
935.60 b |
14.54 b |
17.23 b |
1.56 b |
1.58 b |
3.01 b |
3.10 b |
|
60 |
32.45 a |
40.78 a |
891.0 a |
947.85 a |
15.32 a |
18.13 a |
1.66 a |
1.69 a |
3.15 a |
3.25 a |
|
LSD value at 0.05 |
1.30 |
0.32 |
3.46 |
3.70 |
0.13 |
0.13 |
0.05 |
0.06 |
0.045 |
0.05 |
|
Significance |
|
|
|
|
|
|
|
|
|
|
|
HA types |
** |
** |
** |
** |
** |
** |
** |
** |
** |
** |
|
HA rates |
** |
** |
** |
** |
** |
** |
** |
** |
** |
** |
|
Types × Rates |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
Means following the same letters, within a column for each trait, are
not statistically different from each other at P ≤ 0.05
HA=Humic Acid; **=
Significant at P ≤ 0.01; ns= Non-Significant
Table
3: Effect of humic acid types and rates of application on yield components of
mungbean
|
Treatments |
Branches
plant-1 |
Pods plant-1 |
Pod
length (cm) |
100-seed
weight (g) |
Seed
yield (t ha-1) |
Biomass
yield (t ha-1) |
||||||||
|
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
|||
|
HA types |
|
|
|
|
||||||||||
|
Solid |
20.59 a |
23.68 a |
23.85 a |
28.28 a |
15.25 a |
16.28 a |
1.48 a |
1.69 a |
1.07 a |
1.27 a |
6.54 a |
7.45
a |
||
|
Liquid |
17.73 b |
20.40 b |
19.40 b |
22.95 b |
13.01 b |
13.90 b |
1.38 b |
1.60 b |
0.92 b |
1.08 b |
5.52 b |
6.35
b |
||
|
LSD value at 0.05 |
0.40 |
0.52 |
0.80 |
0.83 |
0.23 |
0.25 |
0.007 |
0.006 |
0.02 |
0.03 |
0.05 |
0.06 |
||
|
HA
rates (kg ha-1) |
||||||||||||||
|
0 |
12.34 d |
16.92 d |
16.45 d |
19.48 d |
10.10 d |
9.75 d |
1.33 d |
1.55 d |
0.91 c |
1.05 c |
5.07 d |
5.81
d |
||
|
20 |
17.35 c |
19.93 c |
19.85 c |
23.52 c |
11.65 c |
12.46 c |
1.38 c |
1.60 c |
0.97 b |
1.13 b |
5.41 c |
6.22
c |
||
|
40 |
21.87 b |
25.20 b |
24.45 b |
28.95 b |
16.81 b |
17.98 b |
1.44 b |
1.65 b |
1.04 a |
1.24 a |
6.65 b |
7.61
b |
||
|
60 |
22.69 a |
27.50 a |
25.68 a |
30.49 a |
17.89 a |
19.18 a |
1.48 a |
1.73 a |
1.05 a |
1.25
a |
6.88 a |
7.86
a |
||
|
LSD value at 0.05 |
0.26 |
0.30 |
0.28 |
0.35 |
0.33 |
0.34 |
0.002 |
0.004 |
0.03 |
0.02 |
0.05 |
0.04 |
||
|
Significance |
|
|
|
|
|
|
|
|
|
|
|
|
||
|
HA types |
** |
** |
* |
* |
* |
** |
** |
** |
** |
** |
** |
** |
||
|
HA rates |
** |
** |
** |
** |
** |
** |
** |
** |
** |
** |
** |
** |
||
|
Types × Rates |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
||
Means following the same letters, within a column for each trait, are
not statistically different from each other at P ≤ 0.05
HA=Humic Acid; *=
Significant at P ≤ 0.05; **= Significant at P ≤ 0.01;
ns= Non-Significant
Humic substances
improve plant growth both directly and indirectly as a result of chemical and biological
humification of animal and plant matter (Shah et al. 2018). Indirectly humic substances improve soil microbiota,
soil structure and soil chemistry; while directly these affect photosynthesis,
respiration rate, enzymatic activities, and carbohydrates assimilation (Dawood et al. 2019). Moreover, HA is an
important and integral part of soil Table 4: Effect of humic
acid types and rates of application on seed quality parameters of mungbean
|
Treatments |
Grain
nitrogen (%) |
Grain
phosphorus (%) |
Grain
potassium (%) |
Grain
protein (%) |
Grain
carbohydrates (%) |
|||||
|
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
2016–2017 |
2017–2018 |
|
|
HA types |
|
|
||||||||
|
Solid |
4.34 a |
4.55 a |
0.38 a |
0.46 a |
1.55 a |
1.69 a |
28.19 |
28.11 |
59.61 |
58.75 |
|
Liquid |
4.34 a |
4.55 a |
0.30 b |
0.36 b |
1.36 b |
1.50 b |
28.06 |
28.64 |
59.00 |
58.24 |
|
LSD value at 0.05 |
ns |
ns |
0.004 |
0.02 |
0.02 |
0.03 |
ns |
ns |
ns |
ns |
|
HA rates (kg ha-1) |
|
|
||||||||
|
0 |
3.64 d |
3.83 d |
0.25 d |
0.26 d |
1.21 d |
1.33 d |
21.75 d |
22.23 d |
d 58.00 |
d 56.75 |
|
20 |
4.11 c |
4.34 c |
0.29 c |
0.33 c |
1.39 c |
1.512 c |
26.73 c |
25.13 c |
c 58.75 |
c 57.75 |
|
40 |
4.72 b |
5.00 b |
0.37 b |
0.43 b |
1.60 b |
1.75 b |
30.54 b |
32.44 b |
b 60.25 |
b 61.35 |
|
60 |
4.95 a |
5.55 a |
0.40 a |
0.49 a |
1.65 a |
1.79 a |
31.55 a |
34.65 a |
a 62.50 |
a 56.50 |
|
LSD value at 0.05 |
0.005 |
0.02 |
0.003 |
0.03 |
0.04 |
0.01 |
0.07 |
0.05 |
0.65 |
0.70 |
|
Significance |
|
|
|
|
|
|
|
|
|
|
|
HA types |
ns |
ns |
** |
** |
** |
** |
ns |
ns |
ns |
ns |
|
HA rates |
** |
** |
** |
** |
** |
** |
** |
** |
** |
** |
|
Types × Rates |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
ns |
Means following the same letters, within a column for each trait, are
not statistically different from each other at P ≤ 0.05
HA=Humic Acid; **=
Significant at P ≤ 0.01; ns= Non-Significant
organic matter which is not only a plant bio-stimulant, instead it is a soil
conditioner that improves soil texture, structure, water holding capacity and
physiochemical features (Khaled and Fawy 2011; Calvo et al. 2014). Due to these features, HA application improved water
and nutrient uptake which in turn resulted in higher LAI, stomatal conductance
and higher synthesis of chlorophyll and carotenoid contents. Nonetheless, SEM
analysis also highlighted more nutrients uptake at higher rate (60 kg ha-1)
of HA application (Fig. 1). Similarly, Trevisan et al. (2011) reviewed the positive impact of humic substances on
uptake of nutrient elements; for example, nitrogen, phosphorus, potassium, Sulpher
and magnesium etc. and concluded that
at varying rates different methods of HA differently affect their uptake. Mora et al. (2010) reported positive effects
of HA on nutrient uptake and gas exchange traits in cucumber. Generally, HA
adheres tightly to cell wall and absorbed by plant roots from where it is
partly transferred to shoots where it affects plant metabolism directly (Nardi et al. 2002).
The well-developed plant canopy
(LAI) and photosynthetic pigments captured more solar radiation, and higher
stomatal conductance enhanced carbon influx leading to higher photosynthesis (Ameri and Tehranifar 2012; Tables 1–3).
Therefore, more accumulation of photo-assimilates resulted in significant
expansion in yield related traits leading to higher mungbean yield in this
study. In another study Waqas et al.
(2014) reported substantial improvement in mungbean yield at higher rates of HA
application due to more availability of nutrients from soil to plants. These
findings are consistent with the results obtained by Bakry et al. (2013) in flax seed and El-Bassiouny et al. (2014) in wheat. Correspondingly, HA types and rates
significantly improved seed quality characteristics of mungbean such as higher
grain nitrogen, phosphorus, potassium contents, and protein and carbohydrates
(Table 4). The significant improvement in grain mineral contents owing to HA
application was chiefly linked with more macro- and micronutrients uptake (Fig.
1; Trevisan et al. 2011). Moreover,
better growth and physiological performance enabled plants to assimilate more
photosynthates which lead to higher grain protein and carbohydrate contents
(Delfine et al. 2005; Ozlem et al. 2017).
Results of this study also
unveiled that solid form of HA application was more beneficial in improving
growth, gas exchange traits, and grain yield and quality of mungbean
(Tables 1–4). The possible reason behind was high staying and adherence
tendency of solid form of HA, which facilitated more uptake of micro and
macro-nutrients (Fig. 1; Shah et al.
2018). This improvement was more dynamic for the increasing rates of solid HA
as compared to liquid because sandy soils have poor holding tendency for liquid
form of HA (Afzal et al. 2017; Khaled
and Fawy 2011). Therefore, the application of HA in solid form seemed more
appropriate choice than liquid form on sandy soils of Saudi Arabia. Earlier
Waqas et al. (2014) and Akhtar et al. (2017) also concluded that solid
form of HA is more suitable than its liquid form to improve mungbean growth and
productivity. The possible reason could be the high affinity of solid HA for
sandy soil that facilitates efficient nutrients and water uptake (Khaled and
Fawy 2011; Shah et al. 2018).
Conclusion
Humic acid application, solid
form in particular, improved mungbean productivity in both years of study.
Therefore, mungbean can be effectively cultivated in prevailing conditions of
Kingdom of Saudi Arabia using humic acid as supplement particularly in solid form at the rate of 60 kg ha-1. The
outcomes of this study provided some future guidelines for the optimization and
adaptability of testing of exotic legume crops in arid conditions of Saudi
Arabia.
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